Plot

Ben Hildebrand and Eric Kirby go parasailing around the waters of Isla Sorna. A creature of unknown species attacks and kills the boat crew as it passes through a fog bank, but Ben detaches the line, and with Eric bound with him, he goes sailing into the wilderness.

Eight weeks later, Dr. Alan Grant has become famous as a result of his heroic acts at Jurassic Park. Ellie Sattler is married and has two children. Grant discusses with Sattler how raptors are far more intelligent than they had previously believed, having a complex social structure and hunting pattern. One afternoon at a dig site, Grant's assistant Billy Brennan demonstrates how he can use a 3D printer to replicate the larynx of a Velociraptor.

Paul and Amanda Kirby, a wealthy couple, arrive and offer Grant funding for his research if he will give them an aerial tour of Isla Sorna. Desperate for research support, Grant reluctantly agrees. He flies there along with Paul, Amanda, Billy, and the Kirbys' mercenary associates, Udesky, Cooper, and their pilot Nash. On the plane, Grant learns that the Kirbys' real plan is to land on the island. When he opposes this, he is knocked out by Cooper and wakes to the sound of Amanda using a megaphone. This attracts a Spinosaurus, which devours Cooper and causes the plane to crash into the forest. The Spinosaurus devours Nash and destroys the plane. Fleeing, the survivors manage to briefly lose the Spinosaurus, only to encounter a Tyrannosaurus rex feasting on a corpse. The Spinosaurus returns, but the group escapes while the two carnivores fight each other. The Spinosaurus overpowers the T. rex and kills it.

Soon after, Grant learns the Kirbys are actually a middle-class divorced couple who are looking for their son Eric and Amanda's boyfriend Ben. Further exploration leads them to find the parasail entangled in a tree with Ben's corpse attached to it. When the group encounters raptor nests, they flee, taking the parasail with them. They find an abandoned InGen compound, where Amanda is ambushed by a raptor. The group manages to trap it, but it escapes and contacts the rest of its pack. During the ensuing chase, the group flees into a herd of Corythosaurus and Parasaurolophus and cause a stampede, separating Grant and Udesky from the others. Grant retrieves Billy's satchel, while Udesky is wounded by the raptors. When Amanda, Paul, and Billy try to help Udesky, they realize it was a trap set by the raptors, one of which then kills Udesky.

Grant suspects the raptors are searching for something while observing two of them communicating. He is then ambushed and cornered by the raptors, but is rescued by Eric, who managed to survive in an overturned water truck. The next day, Grant and Eric hear Paul's satellite phone ringing and are reunited with the Kirbys and Billy. Paul explains that he gave the phone to Nash before he was devoured, and the group sees the Spinosaurus once again, with the phone ringing from inside it. After barely escaping, Grant discovers that Billy took two eggs from the raptor nests and hid them in his satchel to use for funding, which provoked the raptor attacks. He decides to keep the eggs to ensure the group's survival. The group unknowingly enters a large aviary used to house Pteranodons, which attack the group and fly away with Eric. Billy rescues Eric by using Ben's parasail, but is then attacked and seemingly killed by Pteranodons. The rest of the group escapes the aviary, leaving the door unlocked in their panic. They make their way downriver using a boat and encounter several herbivorous dinosaurs on the riverside.

That night, the group hears the phone ringing buried in feces of the Spinosaurus and retrieve it. As rain falls, Grant tries to contact Sattler, but the Spinosaurus attacks the boat. Grant and Paul scare it off for good by setting the boat's fuel on fire. The next day, the group makes their way towards the shoreline, but are surrounded by the raptors once again. Grant has Amanda surrender the eggs and then uses the 3D-printed raptor larynx to confuse the pack, who run off with the eggs. The group flees to the coast and find that Sattler had called in the U.S. Marine Corps and the U.S. Navy to rescue them. They discover that Billy, while seriously injured, is still alive. As they leave the island, they see the Pteranodons flying free, and Grant muses they are looking for new nesting grounds.